content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2012, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * ----------------------
   * AbstractDialLayer.java
   * ----------------------
   * (C) Copyright 2006-2008, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 06-Nov-2006 : Version 1 (DG);
   * 17-Nov-2006 : Added visible flag (DG);
   * 16-Oct-2007 : Implemented equals() and clone() (DG);
   *
   */
  
  package org.jfree.chart.plot.dial;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.util.Arrays;
  import java.util.EventListener;
  import java.util.List;
  
  import javax.swing.event.EventListenerList;
  
  import org.jfree.chart.HashUtilities;
  
  /**
   * A base class that can be used to implement a {@link DialLayer}.  It includes
   * an event notification mechanism.
   *
   * @since 1.0.7
   */
  public abstract class AbstractDialLayer implements DialLayer {
  
      /** A flag that controls whether or not the layer is visible. */
      private boolean visible;
  
      /** Storage for registered listeners. */
      private transient EventListenerList listenerList;
  
      /**
       * Creates a new instance.
       */
      protected AbstractDialLayer() {
          this.visible = true;
          this.listenerList = new EventListenerList();
      }
  
      /**
       * Returns <code>true</code> if this layer is visible (should be displayed),
       * and <code>false</code> otherwise.
       *
       * @return A boolean.
       *
       * @see #setVisible(boolean)
       */
      @Override
      public boolean isVisible() {
          return this.visible;
      }
  
      /**
       * Sets the flag that determines whether or not this layer is drawn by
       * the plot, and sends a {@link DialLayerChangeEvent} to all registered
       * listeners.
       *
       * @param visible  the flag.
       *
       * @see #isVisible()
       */
      public void setVisible(boolean visible) {
          this.visible = visible;
          notifyListeners(new DialLayerChangeEvent(this));
      }
  
      /**
       * Tests this instance for equality with an arbitrary object.
       *
       * @param obj  the object (<code>null</code> permitted).
       *
       * @return A boolean.
       */
      @Override
      public boolean equals(Object obj) {
          if (obj == this) {
              return true;
          }
          if (!(obj instanceof AbstractDialLayer)) {
              return false;
          }
          AbstractDialLayer that = (AbstractDialLayer) obj;
          return this.visible == that.visible;
      }
  
      /**
       * Returns a hash code for this instance.
       *
       * @return A hash code.
       */
      @Override
      public int hashCode() {
          int result = 23;
          result = HashUtilities.hashCode(result, this.visible);
          return result;
      }
  
      /**
       * Returns a clone of this instance.
       *
       * @return A clone.
       *
       * @throws CloneNotSupportedException if there is a problem cloning this
       *     instance.
       */
      @Override
      public Object clone() throws CloneNotSupportedException {
          AbstractDialLayer clone = (AbstractDialLayer) super.clone();
          // we don't clone the listeners
          clone.listenerList = new EventListenerList();
          return clone;
      }
  
      /**
       * Registers an object for notification of changes to the dial layer.
       *
       * @param listener  the object that is being registered.
       *
       * @see #removeChangeListener(DialLayerChangeListener)
       */
      @Override
      public void addChangeListener(DialLayerChangeListener listener) {
          this.listenerList.add(DialLayerChangeListener.class, listener);
      }
  
      /**
       * Deregisters an object for notification of changes to the dial layer.
       *
       * @param listener  the object to deregister.
       *
       * @see #addChangeListener(DialLayerChangeListener)
       */
      @Override
      public void removeChangeListener(DialLayerChangeListener listener) {
          this.listenerList.remove(DialLayerChangeListener.class, listener);
      }
  
      /**
       * Returns <code>true</code> if the specified object is registered with
       * the dataset as a listener.  Most applications won't need to call this
       * method, it exists mainly for use by unit testing code.
       *
       * @param listener  the listener.
       *
       * @return A boolean.
       */
      @Override
      public boolean hasListener(EventListener listener) {
          List<Object> list = Arrays.asList(this.listenerList.getListenerList());
          return list.contains(listener);
      }
  
      /**
       * Notifies all registered listeners that the dial layer has changed.
       * The {@link DialLayerChangeEvent} provides information about the change.
       *
       * @param event  information about the change to the axis.
       */
      protected void notifyListeners(DialLayerChangeEvent event) {
          Object[] listeners = this.listenerList.getListenerList();
          for (int i = listeners.length - 2; i >= 0; i -= 2) {
              if (listeners[i] == DialLayerChangeListener.class) {
                  ((DialLayerChangeListener) listeners[i + 1]).dialLayerChanged(
                          event);
              }
          }
      }
  
      /**
       * Provides serialization support.
       *
       * @param stream  the input stream.
       *
       * @throws IOException  if there is an I/O error.
       * @throws ClassNotFoundException  if there is a classpath problem.
       */
      private void readObject(ObjectInputStream stream)
          throws IOException, ClassNotFoundException {
          stream.defaultReadObject();
          this.listenerList = new EventListenerList();
      }
  
  }
  